Air spring suspension system with variable flow valves

Abstract

An air spring suspension system includes first, second, third, and fourth air spring assemblies configured to support a frame of the vehicle at front and rear suspension/wheel assemblies of the vehicle. A valve block includes a valve. A compressor supplies pressurized gas to the valve block. A reservoir is in fluid communication with the valve block. The air spring suspension system includes first, second, third, and fourth height sensors. First, second, third, and fourth variable flow valves are in fluid communication with the valve of the valve block and the first, second, third, and fourth air spring assemblies, respectively. A pressure sensor senses pressure in the valve block. A vehicle kinematic sensor senses a vehicle kinematic parameter. A controller is configured to control the first, second, third, and fourth variable flow valves in response to the pressure, the first, second, third, and fourth height sensors, and the vehicle kinematic parameter.

What is claimed is: 
     
         1 . An air spring suspension system for a vehicle, comprising:
 first and second air spring assemblies configured to support a frame of the vehicle at front suspension/wheel assemblies of the vehicle;   third, and fourth air spring assemblies configured to support a frame of the vehicle at rear suspension/wheel assemblies of the vehicle;   a valve block including a valve;   a compressor supplying pressurized gas to the valve block;   a reservoir in fluid communication with the valve block;   first, second, third, and fourth height sensors configured to sense heights corresponding to the first, second, third, and fourth air spring assemblies, respectively;   first, second, third, and fourth variable flow valves in fluid communication with the valve of the valve block and the first, second, third, and fourth air spring assemblies, respectively;   a pressure sensor configured to sense a pressure in the valve block;   a vehicle kinematic sensor configured to sense a vehicle kinematic parameter; and   a controller configured to control the first, second, third, and fourth variable flow valves in response to the pressure, the first, second, third, and fourth height sensors, and the vehicle kinematic parameter,   wherein the controller is configured to calculate a valve actuation command for at least one of the first, second, third, and fourth variable flow valves based on an estimated air mass to provide a predetermined movement for at least one of the first, second, third, and fourth air spring assemblies.   
     
     
         2 . The air spring suspension system of  claim 1 , wherein the controller is configured to calculate the valve actuation command further based on a difference between the pressure in the valve block and a pressure of at least one of the first, second, third, and fourth air spring assemblies. 
     
     
         3 . The air spring suspension system of  claim 1 , wherein the valve actuation command is further based on a vehicle motion rate limit. 
     
     
         4 . The air spring suspension system of  claim 1 , wherein the valve actuation command is further based on a vehicle load location estimate. 
     
     
         5 . The air spring suspension system of  claim 1 , wherein the controller is configured to output the valve actuation command when the vehicle is within a pre-determined range of a target trim. 
     
     
         6 . The air spring suspension system of  claim 1 , wherein the controller is configured to modify the valve actuation command using closed-loop control to control a vehicle motion rate below a predetermined motion rate limit. 
     
     
         7 . The air spring suspension system of  claim 1 , wherein the controller is configured to modify the valve actuation command using feed forward control to control a vehicle motion rate below a predetermined rate limit. 
     
     
         8 . The air spring suspension system of  claim 1 , wherein the controller is configured to modify the valve actuation command based on a front/rear offset from a trim difference, a motion volume ratio, and a spring volume ratio. 
     
     
         9 . The air spring suspension system of  claim 1 , wherein the controller is configured to modify the valve actuation command based on a left/right offset from a trim difference. 
     
     
         10 . The air spring suspension system of  claim 1 , further comprising a diagnostic module configured to selectively identify a line leak and an air spring leak corresponding to at least one of the first, second, third, and fourth air spring assemblies in response to the pressure during air spring fill operations of the first, second, third, and fourth air spring assemblies, respectively. 
     
     
         11 . The air spring suspension system of  claim 10 , wherein the diagnostic module is configured to set an air spring diagnostic flag in response to the first, second, third, and fourth height sensors when a difference between a measured vehicle motion and a predetermined vehicle motion is greater than a predetermined threshold during air suspension actuation. 
     
     
         12 . The air spring suspension system of  claim 10 , wherein the diagnostic module is configured to open and close at least one of the first, second, third, and fourth variable flow valves a plurality of times within a predetermined period to unclog a corresponding flow path. 
     
     
         13 . The air spring suspension system of  claim 10 , wherein the diagnostic module is configured to selectively identify the line leak for the at least one of the first, second, third, and fourth variable flow valves when:
 the pressure is less than a first predetermined pressure during the air spring fill operation; and   the pressure is less than a second predetermined pressure when the corresponding one of at least one of the first, second, third, and fourth variable flow valves is closed.   
     
     
         14 . The air spring suspension system of  claim 10 , wherein the diagnostic module is configured to selectively identify the air spring leak for the at least one of the first, second, third, and fourth air spring assemblies when:
 the pressure is less than a first predetermined pressure during the air spring fill operation; and   the pressure is greater than a second predetermined pressure when the corresponding one of at least one of the first, second, third, and fourth variable flow valves is closed.   
     
     
         15 . An air spring suspension system for a vehicle, comprising:
 first and second air spring assemblies configured to support a frame of the vehicle at front suspension/wheel assemblies of the vehicle;   third, and fourth air spring assemblies configured to support a frame of the vehicle at rear suspension/wheel assemblies of the vehicle;   a valve block including a valve;   a compressor supplying pressurized air to the valve block;   a reservoir in fluid communication with the valve block;   first, second, third, and fourth variable flow valves in fluid communication with the valve of the valve block and the first, second, third, and fourth air spring assemblies, respectively;   first, second, third, and fourth height sensors corresponding to the first, second, third, and fourth air spring assemblies, respectively;   a pressure sensor configured to sense a pressure in the valve block; and   a controller including:
 a suspension control module configured to control the first, second, third, and fourth variable flow valves in response to the pressure; and 
 a diagnostic module configured to selectively identify a line leak and an air spring leak corresponding to the first, second, third, and fourth air spring assemblies in response to the pressure during air spring fill operations of the first, second, third, and fourth air spring assemblies, respectively, and the first, second, third, and fourth height sensors. 
   
     
     
         16 . The air spring suspension system of  claim 15 , wherein the diagnostic module is configured to set an air spring diagnostic flag in response to the first, second, third, and fourth height sensors when a difference between a measured vehicle motion and a predetermined vehicle motion is greater than a predetermined threshold during air suspension actuation. 
     
     
         17 . The air spring suspension system of  claim 15 , wherein the diagnostic module is configured to open and close at least one of the first, second, third, and fourth variable flow valves a plurality of times within a predetermined period to unclog a corresponding flow path. 
     
     
         18 . The air spring suspension system of  claim 15 , wherein the diagnostic module is configured to selectively identify the line leak for the at least one of the first, second, third, and fourth variable flow valves when:
 the pressure is less than a first predetermined pressure during the air spring fill operation; and   the pressure is less than a second predetermined pressure when the corresponding one of at least one of the first, second, third, and fourth variable flow valves is closed.   
     
     
         19 . The air spring suspension system of  claim 15 , wherein the diagnostic module is configured to selectively identify the air spring leak for the at least one of the first, second, third, and fourth air spring assemblies when:
 the pressure is less than a first predetermined pressure during the air spring fill operation; and   the pressure is greater than a second predetermined pressure when the corresponding one of at least one of the first, second, third, and fourth variable flow valves is closed.